The Centers for Disease Control and Prevention (CDC) estimate that there are more than one million people living with Human Immunodeficiency Virus (HIV) in the United States and each year there are approximately 56,300 new cases of infection. Transgender women (TGW), (i.e.,biological men who live their lives as women), are at particularly high risk for HIV infection and HIV-related morbidity and mortality. Various studies indicate that TGW have the highest HIV prevalence rates of all gender and sexual minorities. However, research also shows that they are less likely to enter and be retained in HIV care. Consequently, they are more likely to suffer adverse health outcomes and infect others. Even once they know they are HIV-infected, TGW are also less likely than other sexual minorities, such as men who have sex with men and bisexual men, to enter HIV care. Historically, research on gender and sexual minorities has included the transgender population in the collective group of lesbian, gay, and bisexual persons. Recent recommendations by the Office of National AIDS Policy and the Institute of Medicine have cautioned that this combined approach has obscured the differences that exist within and between these populations, and has resulted in inadequate examination of the health needs and experiences of the transgender population. This study aims to address these concerns and will explore TGW's experiences of HIV health care utilization (seeking, entering, or being retained in care). Specifically, it will examine the role of social network factors on TGW's decisions to enter into and remain engaged in care and describe the social dynamics (processes) that undergird their use of HIV care throughout the course of their illness. Given the paucity of research with this population, a grounded theory approach will be used to explore how social network norms influence TGW's decisions about when, where, how, and if to seek HIV care, as well as the patterns and pathways through which they enter, progress through, and are retained in care. HIV/AIDS is one of the most critical public health crises confronting gender and sexual minorities, especially TGW. Findings from this study will facilitate a better understanding of the social factors that determine HIV health care utilization behaviors (entry into and retention in care) of TGW following an HIV diagnosis. In addition, this study will contribute to the state of the science of transgender health by expanding knowledge of health care inequalities and transgender-specific health needs, two priority areas outlined by the Institute of Medicine. Results from this study wil provide a strong foundation for establishing a program of research in gender and sexual minority health. Importantly, the results will also be used to educate health care professionals about the needs of HIV infected TGW and to inform the development of strategies to facilitate HIV health care utilization in this population. PUBLIC HEALTH RELEVANCE: Transgender women (biological men who identify as women) have the highest rates of HIV infection of all gender and sexual minorities, yet are less likely to receive HIV care. Relationships in the social support system and health care encounters within the treatment system influence an individual's decision to seek, enter, and remain engaged in care. This study will provide information that will help us understand the social patterns and pathways of HIV care use among TGW and will contribute to development of social and structural interventions to improve HIV care and health outcomes for transgender women with HIV.